Micro-Electro-Mechanical Systems (MEMS) rate gyroscope (gyros) may be susceptible to a bias error. In the absence of a bias error, the output of a stationary (not rotating) gyroscope should be zero. However, a bias error will cause some amount of output signal from the stationary gyroscope. If uncompensated, such bias errors can lead to large drift errors when used in a navigation device. Typically, the gyroscope is calibrated at the factory before installation in the field. A traditional method to reduce gyroscope bias is to perform a calibration while the gyroscope is stationary.
However, bias errors may not remain constant over time. Accordingly, bias compensation for the gyroscope determined during a factory calibration process may not permanently correct the gyroscope bias. Thus, there may be a need to periodically recalibrate the gyroscope in the field in order to maintain accuracy.
Additionally, the gyroscope may be subject to gain errors. A gain error relates to the accuracy of an amount of degrees of rotation sensed by the gyroscope. For example, if a gyroscope is rotated by 360°, then its output should correspond to 360° of rotation. If the gyroscope has a gain error, the gyroscope output would not correspond to the actual amount of rotation. For example, if the gyroscope has a +10% gain error, the output of the gyroscope would correspond to 396° for an actual rotation of 360°. In this example, gain error compensation is required for an accurate gyroscope output.
Typically, the gyroscope is calibrated at the factory before installation in the field to compensate for gain error. However, there may be a need to periodically recalibrate the gyroscope in the field to compensate for gain error in order to maintain accuracy.